(a) Field of the Invention
The present invention relates to a contact structure of a semiconductor device, a manufacturing method thereof, a thin film transistor array panel including a contact structure, and a manufacturing method thereof.
(b) Description of the Related Art
A wire for a semiconductor device is generally made of a metal having low resistivity such as Al containing metal such as Al and Al alloy for signal transmission with minimized signal delay. However, Al containing metal has poor physical and chemical characteristics such that its contact with other materials is easily corroded to deteriorate the characteristics of the semiconductor device.
In particular, a liquid crystal display (LCD) reinforces contacts of a wire with transparent conductive indium tin oxide (ITO) used for pixel electrodes, which corrodes the wire if made of Al containing metal. Although indium zinc oxide (IZO), which does not erode Al containing metal, is suggested as a substitute for ITO, there is a problem of high contact resistance between IZO and wires. It is also suggested that an additional conductor having good contact characteristic be interposed between the wire and ITO or IZO. However, the additional conductor requires an additional photo etching process to increase the complexity of the manufacturing process and the production cost.
A panel for an LCD usually has a layered structure including several conductive layers and insulating layers and several photolithography steps are required for manufacturing the LCD panel. Since the production cost increase as the number of the photolithography steps increase, it is preferable to reduce the number of the photolithography steps.
In the meantime, a gross test for examining the disconnection of the wires and the failure of thin film transistors (TFTs) formed on the LCD panel is performed by contacting probe tips of a tester with contacts of the wires and applying test signals to the contacts.
However, since the probe tips may not be firmly fixed at one point on the contacts and may slide on the surfaces of the contacts such that they scratch the contacts to be damaged and are coated with remnants. Since ITO and IZO used for the reinforcement of the wires have high resistivity, their remnants coated on the probe tips may increase the contact resistance of the tips to decrease the reliability of the gross test.